I feel that it's all about shot placement. They will all kill when put in the right place.

Now with that being said, it's up to you to decide what broadhead will hit where you aim. A fixed blade on a properly tuned bow will be the most consistent but takes time and effort to get right. A mechanical will fly like your field tips with little effort, but will mask any issues with the way that your bow is tuned. This could affect your arrow flight causing slight accuracy issues and penetration issues.....

All will kill. Muzzy a give you a little more leeway if you hit the shoulder, but you have to make sure not only that your bow is tuned, but also that your arrows are spun to make sure they fly straight. As of right now though, nothing will give a better blood trail that a properly placed rage